Activated Carbons Produced from Mixtures of Synthetic Polymers by Physical and Chemical Activation: Application on MCPA Removal

The production of AC was achieved using the most common industrial and consumer solid waste, namely PET, alone or blended with other synthetic polymer such PAN. The PET-PAN mixture (1:1 W/W %) was subjected to carbonization, with a pyrolysis yield off 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. By mixing PET, as a raw material, with PAN (different ratio), an improvement in the final yield of the AC production, for the same activation time, with CO2, was found.

Activated Carbons Produced from Mixtures of Synthetic Polymers by Physical and Chemical Activation: Application on MCPA Removal

The production of AC was achieved using the most common industrial and consumer solid waste, namely PET, alone or blended with other synthetic polymer such PAN. The PET-PAN mixture (1:1 W/W %) was subjected to carbonization, with a pyrolysis yield off 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. By mixing PET, as a raw material, with PAN (different ratio), an improvement in the final yield of the AC production, for the same activation time, with CO2, was found.

Liquid Mixtures Involving Hydrogenated and Fluorinated Alcohols: Thermodynamics, Spectroscopy, and Simulation

This article reports a combined thermodynamic, spectroscopic, and computational study on the interactions and structure of binary mixtures of hydrogenated and fluorinated substances that simultaneously interact through strong hydrogen bonding. Four binary mixtures of hydrogenated and fluorinated alcohols have been studied, namely, (ethanol + 2,2,2-trifluoroethanol (TFE)), (ethanol + 2,2,3,3,4,4,4-heptafluoro-1-butanol), (1-butanol (BuOH) + TFE), and (BuOH + 2,2,3,3,4,4,4-heptafluoro-1-butanol). Excess molar volumes and vibrational spectra of all four binary mixtures have been measured as a function of composition at 298 K, and molecular dynamics simulations have been performed. The systems display a complex behavior when compared with mixtures of hydrogenated alcohols and mixtures of alkanes and perfluoroalkanes. The combined analysis of the results from different approaches indicates that this results from a balance between preferential hydrogen bonding between the hydrogenated and fluorinated alcohols and the unfavorable dispersion forces between the hydrogenated and fluorinated chains. As the chain length increases, the contribution of dispersion increases and overcomes the contribution of H-bonds. In terms of the liquid structure, the simulations suggest the possibility of segregation between the hydrogenated and fluorinated segments, a hypothesis corroborated by the spectroscopic results. Furthermore, a quantitative analysis of the infrared spectra reveals that the presence of fluorinated groups induces conformational changes in the hydrogenated chains from the usually preferred all-trans to more globular arrangements involving gauche conformations. Conformational rearrangements at the CCOH dihedral angle upon mixing are also disclosed by the spectra.

Production of activated carbons from single and mixtures of synthetic polymers

The production of activated carbons (ACs) involves two main steps: the carbonization of the carbonaceous of raw materials at temperatures below 1073 K in the absence of oxygen and the activation had realized at the temperature up to 1173 but the most useful temperature at 1073 K. In our study we used the most common industrial and consumer solid waste, namely PET, alone or blended with other synthetic polymer PAN. By mixing the two polymers in different ratios, an improvement of the yield of the AC production was found and some textural properties were enhanced by comparison with the AC prepared using each polymer separately. When all the samples were exposed through the carbonization process with a pyrolysis the mixture of PAN-PET (1:1w/w) yield around 31.9%, between that obtained with PET (16.9%) or PAN (42.6%) separately. The combine activation, with CO2 at 1073 K, allow ACs with a lower burn-off degree isothermally, when compared with those attained with PET or PAN alone, but with similarly chemicals or textural properties. The resultant ACs are microporous in their nature, as the activation time increase, the PET-PAN mixture AC are characterized by a better developed porous structure, when associated with the AC prepared from PAN. The AC prepared from PET-PAN mixture are characterized by basic surface characteristics, with a pHpzc around 10.5, which is an important characteristic for future applications on acidic pollutants removals from liquid or gaseous phase. In this study we had used the FTIR methods to determine the main functional groups in the surface of the activated carbons. The adsorbents prepared from PAN fibres presents an IR spectrum with similar characteristics to those obtained with PET wastes, but with fewer peaks and bands with less intensity, in particular for the PAN-8240 sample. This can be reflected by the stretching and deformation modes of NH bond in the range 3100 – 3300 cm-1 and 1520 – 1650 cm-1, respectively. Also, stretching mode associated to C–N, C=N, can contributed to the profile of IR spectrum around 1170 cm-1, 1585 – 1770 cm-1. And the TGA methods was used to study the loses of the precursors mass according to the excessive of the temperature. The results showed that, there were different decreasing of the mass of each precursors. PAN degradation started at almost 573 K and at 1073 K, PAN preserve more than 40% of the initial mass. PET degradation started at 650 K, but at 1073 K, it has lost 80% of the initial mass. However, the mixture of PET-PAN (1:1w/w) showed a thermogravimetric profile between the two polymers tested individually, with a final mass slightly less than 30%. From a chemical point of view, the carbonisation of PET mainly occurs in one step between 650 and 775 K.

Morphological and chemical characterization of tintypes and ambrotypes

The present work was done on two ambrotypes and two tintypes. It aimed evaluate their chemical and physical characteristics, especially their degradation patterns. Moreover, to understand the materials used for their production and cross-check analytical and historical information about the production processes. To do so multi-analytical, non-destructive methods were applied. Technical photography highlighted the surface morphology of the objects and showed the distribution of the protective coatings on their surfaces through UV radiation, which were very different between the four pieces. OM allowed for a detailed observation of the surfaces along with the selection of areas of interest to be analysed with SEM-EDS. SEM-EDS was the technique used most extensively and the one that provided the most insightful results: it allowed to observe the morphology of the image forming particles and the differences between highlights, dark areas and the interfaces between them. Also, elemental point analysis and elemental maps were used to identify the image forming particles as silver and to detect the presence of compounds related to the production, particularly gold used to highlight jewellery, iron as the red pigment and traces of the compounds used in the photographic process containing Ag, I, Na and S . Also, some degradation compounds were analysed containing Ag, Cu, S and Cl. With μ-FT-IR the presence of collodion was confirmed and the source of the protective varnishes was identified, particularly mastic and shellac, in either mixtures of the two or only one. μ-Raman detected the presence of metallic silver and silver chloride on the objects and identified one of the red pigments as Mars red. Finally, μ-XRD showed the presence of metallic silver and silver iodide on both ambrotypes and tintypes and hematite, magnetite and wuestite on the tintypes; RESUMO: O presente estudo foi desenvolvido sobre dois ambrótipos e dois ferrótipos. O propósito consiste em estudar as suas características químicas e físicas, dando particular ênfase aos padrões de degradação. Também é pretendido compreender os materiais usados na sua produção e relacionar esta informação analítca com dados históricos de manuais técnicos contemporâneos à produção dos objectos. Para tal foram utilizadas técnicas multi-analíticas e não destrutivas. O uso da fotografia técnica permitiu uma observação da morfologia das superficies dos objectos e da distribuição das camadas de verniz através da radiação UV, muito diferente entre os quatro. A microscopia óptica proporcionou uma observação detalhada das superfícies assim como a selecção de pontos de interesse para serem analisados com SEM-EDS. SEM-EDS foi a técnica usada mais extensivamente e a que proporcionou os resultados mais detalhados: observação da morofologia das partículas formadoras da imagem e as diferenças entre zonas de altas luzes, baixas luzes e as interfaces entre elas. A análise elemental e os mapas elementares foram usados para detectar prata nas partículas formadoras da imagem e a presença de compostos relacionados com a produção, em particular ouro utilizado para realçar joalharia, ferro no pigmento vermelho e vestígios de compostos utilizados no processo fotográfico incluindo Ag, I, Na e S. Do mesmo modo, alguns compostos de degradação foram analisados contendo Ag, Cu, S e Cl. Com μ-FT-IR a presença de colódio foi confirmada e identificada a origem dos vernizes, mástique e goma-laca, tanto em misturas dos dois como apenas um. Com μ-Raman foi detectada a presença de prata metálica e de cloreto de prata e identificado um dos pigmentos vermelhos como Mars red. Finalmente, μ-DRX revelou a presença de prata metálica e iodeto de prata tanto nos ambrótipos como nos ferrótipos e hematite, magnetite e wuestite nos ferrótipos.